Abraham Lincoln used it as a laxative.

Winston Churchill’s father, Lord Randolph Churchill, used it to treat syphilis. Russian tsar Ivan the Terrible may have been under its influence when he killed his son, Ivan Ivanovich, in 1581.

The first Chinese emperor, Qin Shi Huang, died after drinking it. Ironically, he believed it would prolong his life. 

Medieval alchemists believed it was the “First Matter” from which all other metals were made, and that it could be used to turn lead and other base metals into gold.

Going back even further, the Roman writer Pliny the Elder called it argentum vivum, or “living silver,” in 77 AD. He became one of the first to describe mercury amalgamation — using mercury to capture and separate precious metals, such as gold and silver, from ore or sediment.

He also noted that it was poisonous.

Humankind has a long and complicated relationship with mercury, also known as quicksilver.

With its silver-white appearance, the way it will turn into a roly-poly ball at the prod of a pencil, and that it remains liquid at room temperature, it seems harmless.

But don’t be fooled by its benign appearance. Mercury is toxic to the nervous and immune systems, and prolonged exposure can, among other things, make you as mad as the Hatter that Lewis Carroll introduced us to in Alice’s Adventures in Wonderland. 

Mercury has been mined on the Central Coast since the mid-19th century. There are an estimated 175 sites where people have searched for it, from Cambria to Ventura, the majority being in San Luis Obispo County.

None is active any longer, but the Central Coast was once a major producer of Hydrargyrum — “water silver.”

It has been estimated that Central Coast mercury mines produced as many as 10 million pounds of mercury from when the first mine opened in 1862 to 1970, when the last one closed.

Mercury is 13½ times denser than water, but it will flow like a mountain stream at room temperature — the only metal that will do that.

Fun facts: One cup of mercury weighs more than seven pounds, one gallon weighs 113 pounds, and one standard 55-gallon drum of mercury weighs 6,200 pounds — more than three tons!

Mercury has been used in one form or another dating back at least to ancient Egypt, for it has been found in tombs as old as 1500 BCE.

But it made its influence known in a different way in 1865, when Carroll came up with the Hatter in Alice’s Adventures in Wonderland.

Both the Hatter and the March Hare are referred to as “mad” by the Chesire Cat, and so the term “Mad as a Hatter” became widespread.

But it had actually come into the lexicon of Victorian England as long as 40 years before that.

During the manufacture of hats in the 18th and 19th centuries, workers were often exposed to mercury compounds such as mercuric nitrate, which was used to turn animal fur into felt.

Mercury exposure can cause tremors — known in those days as “hatters’ shakes” — as well as depression, fits of rage, irritability, excitability, slurred speech, loss of memory, paranoia, personality changes — all of which came to be known as “mad hatter disease,” or erethism mercurialis, in the 19th century.

Mercury had been in use in many different ways thousands of years before the Victorians used it to make hats. The ancient Greeks used mercury sulfide in ointments, and the Romans used it in cosmetics.

From the Renaissance until the 19th century, “mercury silvering” was used to coat glass with a mercury-tin amalgam to create mirrors. These mirrors were prized and sought after, but mirror makers often contracted mercury poisoning.

One of the most famous — or infamous — uses of mercury was in treating syphilis. From the 16th century until the early 20th, mercury was the standard treatment for it.

Mercury ointment was rubbed onto the affected area. Some doctors placed patients in cabinets and forced them to breath mercury vapor, sometimes continuing this treatment until the patient salivated heavily, the idea being that the disease was being expelled from the body.

Needless to say, no one was ever cured this way. But because mercury was so universally used in syphilis treatment that people sometimes observed, “A night with Venus, a lifetime with mercury.”

The first mercury was mined on the Central Coast in 1862, with the opening of the “Little Bonanza” mines in the Santa Lucia Mountains.

Near Cambria, the Oceanic Mine began yielding mercury in 1865, and before it closed in 1958 it had produced 38,000 “flasks” of the silvery-white metal.

(Mercury has traditionally been measured in “flasks,” iron containers that were used to safely store and transport it, each holding 76 pounds. Iron is one of the metals with which mercury does not react).

The Klau Mine, in the Paso Robles area, started operations in 1868.

Not much remains of the Central Coast’s mercury mines now, other than abandoned buildings and some rusting equipment that was left behind.

The last to close was the Buena Vista mine, which ceased operations in 1970 after producing more than 15,000 flasks of mercury and is now, due to contamination, a Superfund site.

The Rinconada Mine, near Santa Margarita Lake, is said to be haunted.

Mercury belongs in the same category as cobras, tigers and erupting volcanoes — interesting to see, but it’s best to keep a respectable distance.

Look, but don’t touch, unless you want to end up like the Mad Hatter.